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Štěchovice Reservoir
Štěchovice Reservoir (in Czech ''Vodní nádrž Štěchovice'') is a dam on Vltava River built from 1937 to 1945 as the second stage of the Vltava Cascade. The dam is named after nearby village Štěchovice. The construction started before World War 2 and because of the need for electricity resources were allocated for the project in spite of general shortage. The power station was put in action in 1943. The reservoir had flooded St John's Rapids (''Svatojánské proudy''), the most dangerous but romantic part of Vltava. The main role of the reservoir is to balance the water runoff from peak-load power station at Slapy Dam and to propel two Kaplan turbines with total installed power 2 x 11.25 MW (Štěchovice I). A lock (20.1 m difference between water levels, length 118 m) handles ships with displacement up to 1,000 tons. The reservoir is also used by the pumped-storage hydroelectric plant Štěchovice II whose upper reservoir was created on the top of hill Homole. The pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reservoir
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an embayment within it, through excavation, or building any number of retaining walls or levees. In other contexts, "reservoirs" may refer to storage spaces for various fluids; they may hold liquids or gasses, including hydrocarbons. ''Tank reservoirs'' store these in ground-level, elevated, or buried tanks. Tank reservoirs for water are also called cisterns. Most underground reservoirs are used to store liquids, principally either water or petroleum. Types Dammed valleys Dammed reservoirs are artificial lakes created and controlled by a dam A dam is a barrier that stops or restricts the flow of surface water or underground streams ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lock (water Transport)
A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is the chamber itself (usually then called a caisson) that rises and falls. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken. Pound lock A ''pound lock'' is most commonly used on canals and rivers today. A pound lock has a chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as a flash lock. Pound locks were first used in China during the Song Dynasty (960–1279 AD), having been pioneered by the Song politician and naval en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroelectric Power Stations In The Czech Republic
Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reservoirs In The Czech Republic
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an embayment within it, through excavation, or building any number of retaining walls or levees. In other contexts, "reservoirs" may refer to storage spaces for various fluids; they may hold liquids or gasses, including hydrocarbons. ''Tank reservoirs'' store these in ground-level, elevated, or buried tanks. Tank reservoirs for water are also called cisterns. Most underground reservoirs are used to store liquids, principally either water or petroleum. Types Dammed valleys Dammed reservoirs are artificial lakes created and controlled by a dam constructed across a valley, and rely on the natural topography to provide most of the basin of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hectare
The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about and one hectare contains about . In 1795, when the metric system was introduced, the ''are'' was defined as 100 square metres, or one square decametre, and the hectare ("hecto-" + "are") was thus 100 ''ares'' or km2 (10,000 square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units (), the ''are'' was not included as a recognised unit. The hectare, however, remains as a non-SI unit accepted for use with the SI and whose use is "expected to continue indefinitely". Though the dekare/decare daa (1,000 m2) and are (100 m2) are not officially "accepted for use", they are still used in some contexts. Description The hectare (), although not a unit of SI, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2002 European Floods
In August 2002, a week of intense rainfall produced flooding across a large portion of Europe. It reached the Czech Republic, Italy, Spain, Austria, Germany, Slovakia, Hungary, Romania, Bulgaria, Croatia, Ukraine and Russia. The event killed 232 people and left (US$27.115 billion) in damage. The flood was of a magnitude expected to occur roughly once a century. Unprecedented flood heights were recorded and at least 110 people died. The total economic damage estimates exceeded 15 billion Euros, of which 15% was insured.Helmer, M. & Hilhorst, D.J.M. 2006, "Natural disasters and climate change", Disasters, vol. 30, no. 1, pp. 1–4. Development Flooding resulted from the passage of two Genoa low pressure systems (named Hanne and Ilse by the Free University of Berlin) which brought warm moist air from the Mediterranean northwards. The effects of El Niño may have contributed. The floods gradually moved eastwards along the Danube, although the damage in the large cities on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francis Turbine
The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The process of arriving at the modern Francis runner design took from 1848 to approximately 1920. It became known as the Francis turbine around 1920, being named after British-American engineer James B. Francis who in 1848 created a new turbine design. Francis turbines are primarily used for producing electricity. The power output of the electric generators generally ranges from just a few kilowatts up to 1000 MW, though mini-hydro installations may be lower. The best performance is seen when the head height is between . Penstock diameters are between . The speeds of different turbine units range from 70 to 1000 rpm. A wicket gate around the outside of the turbine's rotating runner controls the rate of water flow through the turbine for d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pumped-storage Hydroelectricity
Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power. Although the losses of the pumping process make the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. If the upper lake collects significant rainfall or is fed by a river then the plant may be a net energy producer in the manner of a traditional hydroelectric plant. Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar, wind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Displacement (fluid)
In fluid mechanics, displacement occurs when an object is largely immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can then be measured, and from this, the volume of the immersed object can be deduced: the volume of the immersed object will be exactly equal to the volume of the displaced fluid. An object that sinks displaces an amount of fluid equal to the object's volume. Thus buoyancy is expressed through Archimedes' principle, which states that the weight of the object is reduced by its volume multiplied by the density of the fluid. If the weight of the object is less than this displaced quantity, the object floats; if more, it sinks. The amount of fluid displaced is directly related (via Archimedes' principle) to its volume. In the case of an object that sinks (is totally submerged), the volume of the object is displaced. In the case of an object that floats, the amount of fluid displaced will be equal in weight to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megawatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Energy transformation, energy transfer. The watt is named after James Watt (1736–1819), an 18th-century Scottish people, Scottish invention, inventor, mechanical engineer, and chemist who improved the Newcomen steam engine, Newcomen engine with his own Watt steam engine, steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution. Overview When an object's velocity is held constant at one metre per second against a constant opposing force of one Newton (unit), newton, the rate at which Work (physics), work is done is one watt. : \mathrm In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potentia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vltava River
Vltava ( , ; german: Moldau ) is the longest river in the Czech Republic, running southeast along the Bohemian Forest and then north across Bohemia, through Český Krumlov, České Budějovice and Prague, and finally merging with the Labe at Mělník. It is commonly referred to as the "Czech national river". Both the Czech name ' and the German name ' are believed to originate from the old Germanic words ' 'wild water' (compare Latin '). In the ' (872 AD) it is called '; from 1113 AD it is attested as '. In the ' (1125 AD) it is attested for the first time in its Bohemian form, '. Course The Vltava River is long and drains an area of in size, over half of Bohemia and about a third of the Czech Republic's entire territory. As it runs through Prague, the river is crossed by 18 bridges (including the Charles Bridge) and covers within the city. The water from the river was used for drinking until 1912 when the Vinohrady Water Tower ceased pumping operations. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaplan Turbine
The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency over a wide range of flow and water level. The Kaplan turbine was an evolution of the Francis turbine. Its invention allowed efficient power production in low-head applications which was not possible with Francis turbines. The head ranges from and the output ranges from 5 to 200 MW. Runner diameters are between . Turbines rotate at a constant rate, which varies from facility to facility. That rate ranges from as low as 54.5 rpm (Albeni Falls Dam) to 450 rpm. Kaplan turbines are now widely used throughout the world in high-flow, low-head power production. Development Viktor Kaplan, living in Brünn, Austria-Hungary (now Brno, Czechia), obtained his first patent for an adjustable blade propeller turbine in 1912. But t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
